TM 5-815-5/AFM 88-5, Chap 6/NAVFAC P-418
U.S. Army Corps of Engineers
Figure 2-13. Recharge of groundwater toprevent settlement of a building as a result of dewatering operations
of dewatering. This information will provide a basis
design elevation without lowering the groundwater
for evaluating any claims that may be made.
level; use a combination of concrete cutoff walls con-
(8) Dewatering versus cutoffs and other proce-
structed in slurry-supported trenches, and a tremied
dures. While dewatering is generally the most ex-
concrete foundation slab, in which case the cutoff
peditious and economical procedure for controlling
walls may serve also as part of the completed struc-
water, it is sometimes possible to excavate more eco-
ture; use large rotary drilling machines for excavating
nomically in the wet inside of a cofferdam or caisson
purposes, without lowering the groundwater level; or
and then seal the bottom of the excavation with a
use freezing techniques. Cofferdams, caissons, and cut-
tremie seal, or use a combination of slurry wall or
off walls may have difficulty penetrating formations
other type of cutoff and dewatering. Where subsurface
containing numerous boulders. Foundation designs re-
construction extends to a considerable depth or where
quiring compressed air will rarely be needed, although
high uplift pressures or large flows are anticipated, it
compressed air may be economical or necessary for
may occasionally be advantageous to: substitute a
some tunnel construction work.
caisson for a conventional foundation and sink it to the
2-14
Previous Page
